Fluidized beds of magnetic ion exchangers exhibit special features because of the additional influence of magnetic forces, which cannot be achieved in conventional fluidized or fixed beds. Specific choice of the magnetic parameters, such as particle magnetization, field strength and frequency of the external magnetic field, allows various operating conditions to be attained, the extremes of which may be described by the terms Magnetically Stabilized Fluidized Bed (MSFB) and Magnetically Stirred Reactor (MSR). The experiments conducted in this work show that liquid fluidized MSFBs exhibit a marked decrease in mass transfer compared to conventional fluidized beds operated under the same conditions. We have demonstrated a correlation between the transition from a fluidized bed to a magnetically stabilized fluidized bed and an increase in the value of a newly defined dimensionless number, M*. Provided that the physical properties (magnetization, density and diameter) of the particles are known, it is then possible to obtain a first estimate with regard to the magnetic field required for attaining an MSFB. The experimental data clearly show that the magnitude of the decrease in liquid-side mass transfer associated with this transition is influenced mainly by the ratio between the flow velocity, u, and the minimum fluidization velocity of the particles, u(mf). Based on this observation, an empirical correlation is presented, which allows an estimation of the Sherwood number, Sh, of an MSFB to be made as a function of the parameters M* and u/u(mf). (C) 2001 Elsevier Science B.V. All rights reserved.